This invention relates generally to timepieces having an analog display, and more particularly to an improved gear train for driving the timekeeping hands of a watch of this type.
In a mechanical watch of the analog type, the hour, minute and seconds hands are driven by a spring-wound motor through a gear train functioning to turn the hour, minute and seconds wheels to which the hands are attached. In an electronic watch of the analog type, the gear train, which turns these wheels, is usually driven by a stepping motor actuated by timed electrical pulses. The present invention is applicable to both electronic and mechanical analog watches.
The invention deals with an analog timepiece whose gear train includes a fixed center pipe on which a free cannon pinion and a tubular extension of an hour wheel concentric therewith are rotatably supported. The disadvantages incident to a prior art arrangement of this type are spelled out in an analysis of the prior art which precedes the detailed description of the invention in a subsequent section of this specification.
The following Swiss patents represent relevant prior art: Swiss Pat. Nos. 342,903; 224,464 and 334,705.